Prostaglandin compositions and methods for the treatment of vasospasm

ABSTRACT

Compositions and methods for the treatment of vasospasm are provided comprising applying an amount of a semi-solid vasoactive prostaglandin composition to the affected tissue. Also provided are methods of improving microcirculation in a replanted body part.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 60/459,896, filed Apr. 2, 2003. The entire content ofthe above application is incorporated herein by reference in entirety.

BACKGROUND OF THE INVENTION

Vasospasm is a constriction of blood vessels, resulting in ischemia ofthe tissue supplied by the blood vessels. Prolonged spasm in arteries,veins, and vein grafts has been described as a physiologic complicationin microsurgery for over 20 years (Buncke, H. J, Microsurgery:Transplantation-Replantation, on-line edition, Chapter 36,http//buncke.org/textbook.html, accessed Dec. 13, 2002). Vasospasmresults from several processes including intrinsic smooth musclecontraction, local noradrenaline metabolism, neurogenic and hormonalprocesses, and prostaglandin metabolism. Topical agents, such asmagnesium sulfate, lidocaine, papaverine and chlorpromazine have beenreported to successfully relieve vasospasm. Other described methods forrelieving vasospasm include nerve blocks, systemic adrenergic agents andsystemic vasodilating agents such as sodium nitroprusside (Buncke,on-line edition, http://buncke.org/book/ch36/ch36_(—)2.html).Experimental attempts to find roles for modifiers of prostaglandinfunction, sympatholytics, calcium channel blockers and numerous otherdrugs have generally not succeeded in producing either clearlyapplicable models or reproducibly positive results (Buncke, on-lineedition, http://buncke.org/book/ch36/ch36_(—)5.html). Vasospasm may beelicited by cold, mechanical trauma or chemical mediators, includingadrenalin.

If circulation is not re-established in time, tissue damage may resultdue to reperfusion injury. Reperfusion injury refers to the cellularchanges and tissue damage seen after a period of total ischemia followedby reperfusion. Extremity replantation, organ transplantation, free flaptissue reconstruction and even myocardial infarction and stroke are allclinical examples of interval tissue ischemia which can lead to tissueloss due to reperfusion injury after blood flow is re-established.Tissue reperfusion injury, seen in its full clinical extent as theno-reflow phenomenon, appears as inflammatory response to reperfusion,resulting in the ultimate death of the tissue.

Prostaglandin E₁ is a derivative of prostanoic acid, a 20-carbon atomlipid acid, represented by the formula:

and is commercially available, e.g., from Chinoin Pharmaceutical andChemical Works Ltd. (Budapest, Hungary) under the designation“Alprostadil USP,” from Pharmacia & Upjohn under the designation“Caveiject”. Prostaglandin E₁ complexed with alpha-cyclodextrin isavailable as alprostatil alfadex from Ono Pharmaceuticals (Japan) and inan injectable form under the designation “Edex®” or “Viradex®” fromSchwarz Pharma (Germany).

Prostaglandin E₁ is a vasodilator useful to maintain open blood vesselsand, therefore, to treat peripheral vascular disease among otherailments. While the potential benefits from transdermal delivery ofprostaglandin E₁ have long been recognized, prior efforts at developinga topical composition for prostaglandin delivery have not been fullysuccessful. Working alone, most drugs, prostaglandin formulationsincluded, do not sufficiently permeate the skin to provide drugconcentration levels comparable to those obtained from other drugdelivery routes. To overcome this problem, topical drug formulationstypically include a skin penetration enhancer. Skin penetrationenhancers also may be referred to as absorption enhancers, accelerants,adjuvants, solubilizers, sorption promoters, etc. Whatever the name,such agents serve to improve drug absorption across the skin. Idealpenetration enhancers not only increase drug flux across the skin, butdo so without irritating, sensitizing, or damaging skin. Furthermore,ideal penetration enhancers should not adversely affect the physicalqualities of the available dosage forms (e.g., cream or gel), or thecosmetic quality of the topical composition.

A wide variety of compounds have been evaluated as to theireffectiveness in enhancing the rate of penetration of drugs through theskin. See, for example, Percutaneous Penetration Enhancers, Maibach H.I. and Smith H. E. (eds.), CRC Press, Inc., Boca Raton, Fla. (1995),which surveys the use and testing of various skin penetration enhancers,and Büyüktimkin et al., Chemical Means of Transdermal Drug PermeationEnhancement in Transdermal and Topical Drug Delivery Systems, Gosh T.K., Pfister W. R., Yum S. I. (Eds.), Interpharm Press Inc., BuffaloGrove, Ill. (1997).

SUMMARY OF THE INVENTION

We have found that administration of prostaglandin compositionscomprising a penetration enhancer relieves constriction of a bloodvessel in vasospasm and restores blood flow. The method and compositionsare useful for the relief of vasospasm in several conditions, includingvasospasm occurring during and following replantation surgery. In otheraspects, the invention provides methods and compositions for improvingmicrocirculation in a replanted body part. In other embodiments, thepresent invention provides methods of treating tissue ischemia. Infurther preferred embodiments, the present invention providescompositions and methods for preventing reperfusion injury.

In one embodiment, the invention provides a method of treating vasospasmin a subject needing such treatment comprising the steps of applying aneffective amount of a semi-solid prostaglandin composition to the regionof the subject's tissue requiring treatment, the composition comprisinga vasoactive prostaglandin; a polymeric thickener selected from thegroup consisting of a polysaccharide gum and a polyacrylic acid polymer;a lipophilic component that is selected from the group consisting of analiphatic C₁ to C₈ alcohol, an aliphatic C₈ to C₃₀ ester and mixturesthereof; water and a buffer system that provides a buffered pH value forthe composition in the range of about 3 to about 7.4. In particularlypreferred embodiments, the composition further comprises a penetrationenhancer. In preferred embodiments, the present invention provides acomposition comprising an effective amount of a vasoactiveprostaglandin; a penetration enhancer selected from the group consistingof an alkyl-(N-substituted amino)alkanoate, analkyl-2-(N,N-disubstituted amino)alkanoate, an (N-substitutedamino)alkanol alkanoate, an (N,N-disubstituted amino)alkanol alkanoate,a pharmaceutically acceptable salt thereof and a mixture thereof; apolymer thickener selected from the group consisting of a polyacrylicacid polymer, a polysaccharide gum, a modified polysaccharide gum andmixtures thereof; a lipophilic component; water and a buffer system,wherein the pH of the composition is 3 to 7.4. The composition may beapplied topically to the skin, parenterally (e.g., subcutaneously) ordirectly to exposed tissues such as the vascular extima of blood vesselsduring surgery or wound treatment.

The vasoactive prostaglandin is suitably selected from the groupconsisting of PGE₁, PGA₁, PGB₁, PGF_(1α), 19-hydroxy-PGA₁,19-hydroxy-PGB₁, PGE₂, PGA₂, PGB₂, 19-hydroxy-PGA₂, 19-hydroxy-PGB₂,PGE₃, PGF_(3α), a pharmaceutically acceptable salt thereof, a loweralkyl ester thereof and a mixture thereof. Preferably, the vasoactiveprostaglandin is selected from the group consisting of prostaglandin E₁,prostaglandin E₂, a pharmaceutically acceptable salt thereof, a loweralkyl ester thereof and a mixture thereof. In preferred embodiments, thevasoactive prostaglandin is PGE₁. If the vasoactive prostaglandin isPGE₁, the dose per application is suitably at least about 0.08 mg PGE₁,preferably about 0.08 mg to about 0.64 mg PGE₁.

In some preferred embodiments, the composition exhibits non-Newtonianrheological properties, suitably comprising a shear-thinningpolysaccharide gum or a shear-thinning polyacrylic acid polymer. In oneembodiment, the composition is thixotropic. In another embodiment, thecomposition is pseudoplastic. In preferred embodiments, the compositionhas a viscosity of about 5,000 centipoise (cps) to about 20,000 cps,more preferably from about 7,000 cps to about 13,000 cps.

In preferred embodiments, the shear-thinning polysaccharide gum is agalactomannan gum or a modified galactomannan gum. A preferred modifiedgalactomannan gum is a modified guar gum. In one embodiment, thepenetration enhancer is dodecyl 2-(N,N-dimethylamino)-propionate or apharmaceutically acceptable salt thereof. In another embodiment, thepenetration enhancer comprises a mixture of lauric acid, isopropylmyristate and triethanolamine. In one embodiment, the lipophiliccomponent comprises at least one aliphatic C₈ to C₃₀ ester. In apreferred embodiment, the lipophilic component comprises at least oneglyceryl ester selected from the group consisting of monoglycerides,diglycerides, triglycerides, and mixtures thereof. In anotherembodiment, the lipophilic component comprises at least one glycerylester selected from the group consisting of glyceryl monooleate,triolein, trimyristin, tristearin, and mixtures thereof.

Typically, the acidic buffer system provides a buffered pH value forsaid composition in the range of about 3 to about 7.4, more preferablyabout 3.0 to about 6.5, most preferably from about 3.5 to about 6.0. Incertain embodiments the composition further comprises an emulsifierselected from the group consisting of sucrose esters, polyoxyethylenesorbitan esters, long chain alcohols, and glyceryl esters. Suitably, theemulsifier comprises at least one glyceryl ester selected from the groupconsisting of glyceryl monooleate, triolein, trimyristin, tristearin,and mixtures thereof. Optionally, the composition further comprises afragrance. In some embodiments the composition further comprises up toabout 5 percent myrtenol, based on the total weight of the composition.Suitably, the composition further comprises a preservative. In otherembodiments, the composition further comprises a topical anesthetic.

In preferred embodiments, the present invention provides a method ofpreventing reperfusion injury of ischemic tissue by providing acomposition of the present invention, applying the composition to thesurface of the affected tissue, and optionally, applying the compositionto the vascular extima of blood vessels supplying the affected tissue.In preferred embodiments, the vascular perfusion volume to the tissuereturns to normal within 30 minutes, more preferably in 10 minutes,optimally less than 10 minutes after the application of the composition.In other aspects, the present invention provides a composition useful inthe manufacture of a medicament for the treatment of vasospasm, forimproving local microcirculation, especially in a replanted body part,or for preventing reperfusion injury.

Other and further aims, purposes, features, advantages, embodiments andthe like will be apparent to those skilled in the art from the presentspecification and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows images of the transilluminated shaved dorsal surfaces ofthe right (FIG. 1A) and left ears (FIG. 1B) of a rabbit. The two arrowsin each Fig. indicate the vasospasm that was observed 5 minutes afterinjections of 2 ml of a 0.1% adrenaline solution into the tissue next tothe central arteries and veins near the base of both ears.

FIG. 2 shows images of the transilluminated shaved dorsal surfaces ofthe right (FIG. 2A) and left ears (FIG. 2B) of the rabbit of FIG. 1about five minutes after topical application of 125 mg of a topicalcomposition comprising 0.4 weight percent (wt %) PGE, onto the skinadjacent to the central artery and vein near the bottom of the right ear(FIG. 2A). At 15 minutes post application, all blood vessels on theright ear were dilated, including the site of the vasospasm (between thetwo arrows). All blood vessels were dilated normally and showed goodcirculation thirty-five minutes after the application. In comparison,the blood vessels of the left ear that was treated with the blankcontrol remained in vasospasm (arrows, FIG. 2B).

FIG. 3 is a graphical representation of the averaged results of a studyof vasospasm in rabbit ears that is illustrated by FIG. 1 and FIG. 2. Asnoted above, a single administration of 80 mg topical composition withvarious PGE, concentrations was applied onto the skin area, 0.5-2 cmabove the ear base, 10 minutes after the typical time a vasospasmappeared in the central ear artery. Administration of the topicalcomposition comprising 0.1, 0.2, 0.4 or 0.8 weight percent PGE, providedrespective doses of 80 (filled circles), 160 (filled triangles), 320(“X”) and 640 (“*”) micrograms (μg) of PGE, as well as cream withoutPGE, (0 μg PGE₁, filled diamonds) and positive control (0.4% PGE,topical composition without penetration enhancer, filled circles).

FIG. 4 is a graphical representation of the averaged results of a studyof vascular perfusion volume in vasospasm in rabbit ears as measured bytranscutaneous laser Doppler blood flowmetry. As noted above, a singleadministration of 80 mg topical composition with various PGE,concentrations was applied onto the skin area, 0.5-2 cm above the earbase, 10 minutes after the typical time a vasospasm appeared in thecentral ear artery. Administration of the topical composition comprising0.1, 0.2, 0.4 or 0.8 weight percent PGE₁ provided respective doses of 80(filled circles), 160 (filled triangles), 320 (“X”) and 640 (“*”)micrograms (μg) of PGE, as well as cream without PGE, (0 μg PGE₁, filleddiamonds) and positive control (0.4% PGE, topical composition withoutpenetration enhancer, filled circles). Measurements were taken of thenormal condition of the blood vessels after anesthesia, at 10 minutesafter vasospasm was induced, and at 10, 15, 30, 60, 90 and 120 minutesafter the administration of the various PGE, compositions. Data arepresented as mean±standard deviation. S* refers to the time of thevasospasm; A** refers to the time of the administration of topicalcomposition.

FIG. 5A and FIG. 5B show ultrasonograms of blood flow in the femoralartery of a rabbit.

FIG. 6 is a graphical representation of the averaged results of a studyof vascular perfusion volume in vasospasm in rabbit femoral artery asmeasured by ultrasonography. As noted above, a single administration of40 mg of a topical composition with various PGE, concentrations wasapplied to the surface of a surgically exposed portion of a femoralartery, 10 minutes after the application of adrenaline hydrochloride.Administration of the topical composition comprising 0.1, 0.2, 0.4 or0.8 weight percent PGE, provided respective doses of 80 (filledcircles), 80 (filled triangles), 160 (“X”) and 320 (“*”) micrograms (μg)of PGE, as well as cream without PGE, (0 μg PGE₁, filled diamonds) and160 μg PGE, topical composition without DDAIP (filled circles).Measurements were taken of the normal condition of the blood vesselsafter anesthesia, at 5 and 10 minutes after vasospasm was induced, andat 5, 10, 15, 30, 60, 90 and 120 minutes after the administration of thevarious PGE, compositions. Data are presented as mean±standarddeviation. S* refers to the time of the vasospasm; A** refers to thetime of the administration of topical composition.

DETAILED DESCRIPTION OF THE INVENTION

Vasospasm is a recognized problem that limits the success ofreplantation of body parts such as fingers, arms and legs. Even ifmicrosurgery is performed to reconnect severed blood vessels, vasospasmcan impair the surgeon's ability to suture during surgery, and can blockpost-surgery blood flow to the reattached limb. When the vasospasmoccurs before the microsurgery, the blood vessels can be so rigid thatthe surgeon is unable to perform the anastomosis. If the vasospasmoccurs after the microsurgery, the blood vessel on one side of theanastomosis could get so rigid that blood flow was blocked.

Current treatment with vasodilators has a success rate around 20%, andeffects are not seen for 30-60 minutes or longer. If the treatment withcurrent therapy is a failure, tissue damage due to ischemia beyond theregion of vasospasm causes the loss of the reattached limb. In suchcases, the surgeon must amputate the limb, causing additional sufferingto the subject, and involving additional expense and hospitalizationtime.

In general, treatment with the methods and topical prostaglandincompositions of the present invention produced an increase in blood flowthrough the region of vasospasm within about five minutes. The treatmenthas a high success rate in early clinical studies, approaching 100%effectiveness. In these studies, the subjects were patients who weretreated and studied at Beijing Jishuitan Hospital. Arms, legs or fingersof the patients, generally severed because of automobile or factoryaccidents, were reattached (replantation) involving microsurgery forarterial anastomosis.

Definitions

Unless otherwise stated, the following terms used in this application,including the specification and claims, have the definitions givenbelow. It must be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise.

“Alkyl” means the monovalent linear or branched saturated hydrocarbonradical, consisting solely of carbon and hydrogen atoms, having from oneto twenty carbon atoms inclusive, unless otherwise indicated. Examplesof an alkyl radical include, but are not limited to, methyl, ethyl,propyl, isopropyl, isobutyl, sec-butyl, tert-butyl, pentyl, n-hexyl,octyl, dodecyl, tetradecyl, eicosyl, and the like.

“Lower alkyl” means the monovalent linear or branched saturatedhydrocarbon radical, consisting solely of carbon and hydrogen atoms,having from one to six carbon atoms inclusive, unless otherwiseindicated. Examples of a lower alkyl radical include, but are notlimited to, methyl, ethyl, propyl, isopropyl, tert-butyl, n-butyl,n-hexyl, and the like.

“Lower alkoxy” means the radical —O—R, wherein R is a lower alkylradical as defined above. Examples of a lower alkoxy radical include,but are not limited to, methoxy, ethoxy, isopropoxy, and the like.

“Halogen” means the radical fluoro, bromo, chloro, and/or iodo.

“Optional” or “optionally” means that the subsequently described eventor circumstance may but need not occur, and that the descriptionincludes instances where the event or circumstance occurs and instancesin which it does not. For example, “optional bond” means that the bondmay or may not be present, and that the description includes single,double, or triple bonds.

“Pharmaceutically acceptable” means that which is useful in preparing apharmaceutical composition that is generally safe, non-toxic, andneither biologically nor otherwise undesirable and includes that whichis acceptable for veterinary as well as human pharmaceutical use.

A “pharmaceutically acceptable salt” of a compound means a salt that ispharmaceutically acceptable, as defined above, and that possesses thedesired pharmacological activity of the parent compound. Such saltsinclude:

1. acid addition salts formed with inorganic acids such as hydrochloricacid, hydrobromic acid, hydrofluoric acid, hydroiodic acid,trifluoroacetic acid, sulfurric acid, nitric acid, phosphoric acid,boric acid and the like; or formed with organic acids such as aceticacid, benzenesulfonic acid, benzoic acid, camphorsulfonic acid,p-chlorobenzenesulfonic acid, cinnamic acid, citric acid,cylcopentanepropionic acid, ethanesulfonic acid, 1,2-ethanedisulfonicacid, formic acid, fumaric acid, glucoheptonic acid, gluconic acid,glutamic acid, glycolic acid, hexanoic acid, heptanoic acid,o-(hydroxybenzoyl)benzoic acid, hydroxynaphtoic acid,2-hydroxyethanesulfonic acid, lactic acid, lauryl sulfuric acid, maleicacid, malic acid, malonic acid, mandelic acid, methanesulfonic acid,4-methylbicyclo[2.2.2]oct-2-ene-1-carboxylic acid,4,4′-methylenebis(3-hydroxy-2-ene-1-carboxylic acid), muconic acid,2-naphthalenesulfonic acid, oxalic acid, 3-phenylpropionic acid,propionic acid, pyruvic acid, salicylic acid, stearic acid, succinicacid, tartaric acid, tertiary butylacetic acid, p-toluenesulfonic acid,trifluoromethanesulfonic acid, trimethylacetic acid, and the like; or

2. salts formed when an acidic proton present in the parent compoundeither is replaced by a metal ion, e.g., an alkali metal ion, analkaline earth ion, or an aluminum ion; or coordinates with an organicor inorganic base. Acceptable organic bases include diethanolamine,ethanolamine, N-methylglucamine, triethanolamine, tromethamine,methylamine, ethylamine, hydroxyethylamine, propylamrine, dimethylamine,diethylamine, trimethylamine, triethylamine, ethylenediamine,hydroethylamine, morpholine, piperazine, and guanidine and the like.Acceptable inorganic bases include aluminum hydroxide, ammoniumhydroxide, calcium hydroxide, potassium hydroxide, sodium carbonate,sodium hydroxide and hydrazine. The preferred pharmaceuticallyacceptable salts are the salts formed from hydrochloric acid, andtrifluoroacetic acid.

“Subject” means mammals and non-mammals. “Mammals” means any member ofthe class Mammalia including, but not limited to, humans, non-humanprimates such as chimpanzees and other apes and monkey species; farmanimals such as cattle, horses, sheep, goats, and swine; domesticanimals such as rabbits, dogs, and cats; laboratory animals includingrodents, such as rats, mice, and guinea pigs; and the like. Examples ofnon-mammals include, but are not limited to, birds, and the like. Theterm “subject” does not denote a particular age or sex.

A “therapeutically effective amount” means an amount of a compound that,when administered to a subject for treating a disease, is sufficient toeffect such treatment for the disease. The “therapeutically effectiveamount” will vary depending on the compound, the disease state beingtreated, the severity or the disease treated, the age and relativehealth of the subject, the route and form of administration, thejudgement of the attending medical or veterinary practitioner, and otherfactors.

The term “pharmacological effect” as used herein encompasses effectsproduced in the subject that achieve the intended purpose of a therapy.In one preferred embodiment, a pharmacological effect means thatvasospasm symptoms of the subject being treated are prevented,alleviated, or reduced. For example, a pharmacological effect would beone that results in the prevention or reduction of vasospasm in atreated subject.

“Disease state” means any disease, condition, symptom, or indication.

“Treating” or “treatment” of a disease state includes:

1. preventing the disease state, i.e. causing the clinical symptoms ofthe disease state not to develop in a subject that may be exposed to orpredisposed to the disease state, but does not yet experience or displaysymptoms of the disease state,

2. inhibiting the disease state, i.e., arresting the development of thedisease state or its clinical symptoms, or

3. relieving the disease state, i.e., causing temporary or progressiveregression of the disease state or its clinical symptoms.

“Pro-drug” means a pharmacologically inactive form of a compound whichmust be metabolized in vivo by a subject after administration into apharmacologically active form of the compound in order to produce thedesired pharmacological effect. After administration to the subject, thepharmacologically inactive form of the compound is converted in vivounder the influence of biological fluids or enzymes into apharmacologically active form of the compound. Although metabolismoccurs for many compounds primarily in the liver, almost all othertissues and organs, especially the lung, are able to carry out varyingdegrees of metabolism. Pro-drug forms of compounds may be utilized, forexample, to improve bioavailability, mask unpleasant characteristicssuch as bitter taste, alter solubility for intravenous use, or toprovide site-specific delivery of the compound. Reference to a compoundherein includes pro-drug forms of a compound.

In a preferred embodiment, the pharmaceutical composition comprises atleast one vasoactive prostaglandin, preferably prostaglandin E₁, apenetration enhancer, a polymeric thickener, a lipophilic component,water and a buffer system that provides a buffered pH value for saidcomposition in the range of about 3 to about 7.4. In one preferredembodiment, the penetration enhancer is an alkyl (N-substituted amino)ester or a pharmaceutically acceptable salt thereof.

Vasoactive prostaglandins are those that act as peripheral vasodilators,including naturally occurring prostaglandins such as PGE₁, PGA₁, PGB₁,PGF_(1α), 19-hydroxy-PGA₁, 19-hydroxy-PGB₁, PGE₂, PGA₂, PGB₂,19-hydroxy-PGA₂, 19-hydroxy-PGB₂, PGE₃, PGF₃,; semisynthetic orsynthetic derivatives of natural prostaglandins, including carboprosttromethamine, dinoprost tromethamine, dinoprostone, lipoprost,gemeprost, metenoprost, sulprostone and tiaprost. Prostaglandin E₁ andprostaglandin E₂ are particularly preferred vasoactive prostaglandinsfor use in conjunction with the present method.

Additionally, simultaneous administration of one or more non-ecosanoidvasodilators may be desirable and may in some cases exhibit asynergistic effect. The combination of prazosin with prostaglandin E₁has been found to be particularly advantageous in this regard.

Suitable non-ecosanoid vasodilators include, but are not limited to:nitrates such as nitroglycerin, isosorbide dinitrate, erythrityltetranitrate, amyl nitrate, sodium nitroprusside, molsidornine,linsidomine chlorhydrate (“SIN-1”) andS-nitroso-N-acetyl-d,l-penicillamine (“SNAP”); amino acids such asL-arginine; long and short acting α-adrenergic blockers such asphenoxybenzaamine, dibenamine, phentolamine, tamsulosin and indoramin,especially quinazoline derivatives such as alfuzosin, bunazosin,doxazosin, terazosin, prazosin, and trimazosin; vasodilative naturalherbal compositions and bioactive extracts thereof, such asgosyajinki-gan, Satureia obovata, bai-hua qian-hu, lipotab, saiboku-to,vinpocetine, Gingko biloba, bacopa, Gynostemma pentaphyllum,gypenosides, Evodia rutaecarpa, rutaecarpine, dehydroevodiamine,danshen, salviae miltiorrhizae radix, shosaikoto, Zizyphi fructus,ginseng and mixtures thereof (U.S. Pat. No. 6,007,824); ergot alkaloidssuch as ergotamine and ergotamine analogs, e.g., acetergamine,brazergoline, bromerguride, cianergoline, delorgotrile, disulergine,ergonovine maleate, ergotamine tartrate, etisulergine, lergotrile,lysergide, mesulergine, metergoline, metergotamine, nicergoline,pergolide, propisergide, proterguride and terguride; antihypertensiveagents such as diazoxide, hydralazine and minoxidil; vasodilators suchas nimodepine, pinacidil, cyclandelate, dipyridamole and isoxsuprine;chlorpromazine; haloperidol; yohimbine; trazodone and vasoactiveintestinal peptides.

Prostaglandin E₁ is well known to those skilled in the art. Referencemay be had to various literature references for its pharmacologicalactivities, side effects, and normal dosage ranges. See for example,Physician's Desk Reference, 51st Ed. (1997), The Merck Index, 12th Ed.,Merck & Co., N.J. (1996), and Martindale The Extra Pharmacopoeia, 28thEd., London, The Pharmaceutical Press (1982). Prostaglandin E₁ as wellas other compounds referenced herein are intended to encompasspharmaceutically acceptable derivatives including physiologicallycompatible salts and ester derivatives thereof.

The quantity of vasoactive prostaglandin, such as prostaglandin E₁, inthe pharmaceutical composition is a therapeutically effective amount andnecessarily varies according to the desired dose, the dosage form (e.g.,suppository or topical), and the particular form of vasoactiveprostaglandin used. The term “prostaglandin” as used generically hereinrefers to the prostaglandin free acid and pharmaceutically acceptablederivatives thereof, including, for example PGE₁, pharmaceuticallyacceptable salts and lower alkyl esters thereof (the term “lower alkyl”as used herein means straight chain or branched chain alkyl containingone to four carbon atoms). The composition generally contains between0.001 percent to 1 percent of vasoactive prostaglandin, e.g.,prostaglandin E₁, typically contains between 0.05 percent to 1 percent,preferably from 0.1 percent to 0.5 percent, based on the total weight ofthe composition.

When used in combination with a vasoactive prostaglandin, a piperazinylquinazoline antihypertensive, such as prazosin, is present in the amountof about 0.1 mg to about 2.0 mg per unit dose, depending on the potencyof the particular piperazinyl quinazoline antihypertensive and the typeand dose of vasoactive prostaglandin used. The dose and the proportionof vasoactive prostaglandin and the piperazinyl quinazolineantihypertensive can be routinely determined by one of ordinary skillwithout undo experimentation.

Working alone, most drugs, prostaglandin formulations included, do notsufficiently permeate the skin to provide drug concentration levelscomparable to those obtained from other drug delivery routes. Toovercome this problem, topical drug formulations typically include askin penetration enhancer. Skin penetration enhancers also may bereferred to as absorption enhancers, accelerants, adjuvants,solubilizers, sorption promoters, etc. Whatever the name, such agentsserve to improve drug absorption across the skin. Ideal penetrationenhancers not only increase drug flux across the skin, but do so withoutirritating, sensitizing, or damaging skin. Furthermore, idealpenetration enhancers should not adversely affect the physical qualitiesof the available dosage forms (e.g. cream or gel), or the cosmeticquality of the topical composition.

A wide variety of compounds have been evaluated as to theireffectiveness in enhancing the rate of penetration of drugs through theskin. See, for example, Percutaneous Penetration Enhancers, Maibach H.I. and Smith H. E. (eds.), CRC Press, Inc., Boca Raton, Fla. (1995),which surveys the use and testing of various skin penetration enhancers,and Büyüktimkin et al., Chemical Means of Transdermal Drug PermeationEnhancement in Transdermal and Topical Drug Delivery Systems, Gosh T.K., Pfister W. R., Yum S. I. (Eds.), Interpharm Press Inc., BuffaloGrove, Ill. (1997). Suitable penetration enhancers for use inprostaglandin topical compositions are disclosed in U.S. Pat. Nos.4,980,378, 5,082,866 and 6,118,020, and published international patentapplication WO 95/09590. Topical compositions employing such penetrationenhancers for the delivery of prostaglandins are disclosed in U.S. Pat.Nos. 6,046,244, 6,323,241, 6,414,028, and 6,489,207.

The topical composition of the present invention can contain one or morepenetration enhancers. Among the preferred penetration enhancers for thepresent invention are ethanol, propylene glycol, glycerol, ethyllaurate, triethanolamine, isopropyl palmitate, isopropyl myristate,lauric acid, laurocapram (Azone™), dioxolanes (described in U.S. Pat.No. 4,861,764), macrocyclic ketones, HP-101, oxazolidones andbiodegradable penetration enhancers (described in U.S. Pat. Nos.4,980,378 and 5,082,866 to Wong et al. such asalkyl-2-(N,N-disubstituted amino) alkanoates (e.g., dodecylN,N-dimethylamino isoproprionate (DDAIP)), N,N-disubstituted aminoalkanol alkanoates (WO 95/09590) and mixtures thereof. When present,isopropyl myristate is present in the amount of about 0.1 to about 10weight percent, preferably about 3 weight percent. When present,triethanolamine is present in the amount of about 0.1 to about 5 weightpercent, preferably about 0.5 weight percent. When present, lauric acidis present in the amount of about 0.1 to about 5 weight percent,preferably about 1 weight percent.

The penetration enhancer is present in an amount sufficient to enhancethe penetration of the vasoactive prostaglandin, e.g., prostaglandin E₁.The specific amount varies necessarily according to the desired releaserate and the specific form of prostaglandin E₁ used. Generally, thepenetration enhancer is present in an amount ranging from about 0.5weight percent to about 20 weight percent, based on the total weight ofthe composition. Preferably, the penetration enhancer is present in anamount ranging from about 1 weight percent to about 10 weight percent ofthe composition. More preferably, the penetration enhancer is present inan amount ranging from about 1 weight percent to about 5 weight percentof the composition.

In general, suitable penetration enhancers can be chosen from thoselisted above as well as sulfoxides, alcohols, fatty acids, fatty acidesters, polyols, amides, surfactants, terpenes, alkanones, organic acidsand mixtures thereof. See generally Chattaraj, S. C. and Walker, R. B.,Penetration Enhancer Classification, pp. 5-20 in Maibach, H. I., andSmith, H. E., (eds.), Percutaneous Penetration Enhancers, CRC Press,Inc., Boca Raton, Fla. (1995) and Büyüktimkin, N., et al., ChemicalMeans of Transdermal Drug Permeation Enhancement, in Gosh, T. K., etal., (eds.) Transdermal and Topical Drug Delivery Systems, InterpharmPress, Inc., Buffalo Grove, Ill. (1997). Suitable sulfoxides includedimethylsulfoxide, decylmethylsulfoxide and mixtures thereof. Suitablealcohols include ethanol, propanol, butanol, pentanol, hexanol, octanol,nonanol, decanol, 2-butanol, 2-pentanol, benzyl alcohol, caprylicalcohol, decyl alcohol, lauryl alcohol, 2-lauryl alcohol, myristylalcohol, cetyl alcohol, stearyl alcohol, olcyl alcohol, linolyl alcohol,linolenyl alcohol and mixtures thereof. Suitable fatty acids includevaleric, heptanoic, pelargonic, caproic, capric, lauric, myristic,stearic, oleic, linoleic, linolenic, caprylic, isovaleric, neopentanoic,neoheptanoic, neononanoic, trimethyl hexanoic, neodecanoic andisostearic acids and mixtures thereof.

Suitable fatty acid esters include isopropyl n-butyrate, isopropyln-hexanoate, isopropyl n-decanoate, isopropyl myristate, isopropylpalmitate, octyldodecyl myristate, ethyl acetate, butyl acetate, methylacetate, methylvalerate, methylpropionate, diethyl sebacate, ethyloleate, ethyl laurate and mixtures thereof. Suitable polyols includepropylene glycol, polyethylene glycol, ethylene glycol, diethyleneglycol, triethylene glycol, dipropylene glycol, glycerol, propanediol,sorbitol, dextrans, butanediol, pentanediol, hexanetriol and mixturesthereof.

Suitable amides include urea, dimethylacetamide, diethyltoluamide,dimethylformamide, dimethyloctamide, dimethyldecamide,1-alkyl-4-imidazolin-2-one, pyrrolidone derivatives, cyclic amides,hexamethylenelauramide and its derivatives, diethanolamine,triethanolamine and mixtures thereof. Suitable pyrrolidone derivativesinclude 1-methyl-2-pyrrolidone, 2-pyrrolidone, 1-lauryl-2-pyrrolidone,1-methyl-4-carboxy-2-pyrrolidone, 1-hexyl-4-carboxy-2-pyrrolidone,1-lauryl-4-carboxy-2-pyrrolidone, 1-decyl-thioethyl-2-pyrrolidone(HP-101), 1-methyl-4-methoxycarbonyl-2-pyrrolidone,1-hexyl-4-methoxycarbonyl-2-pyrrolidone,1-lauryl-4-methoxycarbonyl-2-pyrrolidone, N-cyclohexylpyrrolidone,N-dimethylaminopropylpyrrolidone, N-cocoalkypyrrolidone,N-tallowalkypyrrolidone, fatty acid esters ofN-(2-hydroxymethyl)-2-pyrrolidone and mixtures thereof. Suitable cyclicamides include 1-dodecylazacycloheptane-2-one (laurocapram, Azone®),1-geranylazacycloheptan-2-one, 1-farnesylazacycloheptan-2-one,1-geranylgeranylazacycloheptan-2-one,1-(3,7-dimethyloctyl)azacycloheptan-2-one,1-(3,7,11-trimethyloctyl)azacycloheptan-2-one,1-geranylazacyclohexane-2-one, 1-geranylazacyclopentan-2,5-dione,1-farnesylazacyclopentan-2-one and mixtures thereof.

Suitable surfactants include anionic surfactants, cationic surfactants,nonionic surfactants, bile salts and lecithin. Suitable anionicsurfactants include sodium laurate, sodium lauryl sulfate and mixturesthereof. Suitable cationic surfactants include cetyltrimethylammoniumbromide, tetradecyltrimethylammonium bromide, benzalkonium chloride,octadecyltrimethylammonium chloride, cetylpyridinium chloride,dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride,and mixtures thereof. Suitable nonionic surfactants includeα-hydro-ω-hydroxy-poly(oxyethylene)-poly(oxypropyl)poly(oxyethylene)block copolymers, polyoxyethylene ethers,polyoxyethylene sorbitan esters, polyethylene glycol esters of fattyalcohols and mixtures thereof. Suitableα-hydro-ω-hydroxy-poly(oxyethylene)poly(oxypropyl)poly(oxyethylene)blockcopolymers include Poloxamers 231, 182, and 184 and mixtures thereof.Suitable polyoxyethylene ethers include 4-lauryl ether (Brij 30), (Brij93), (Brij 96), 20-oleyl ether (Brij 99) and mixtures thereof. Suitablepolycxyethylene sorbitan esters include the monolaurate (Tween 20, Span20) the monopalmitate (Tween 40), the monostearate (Tween 60), and themonooleate (Tween 80) and mixtures thereof. Suitable polyethylene glycolesters of fatty acids include the 8-oxyethylene stearate ester (Myj 45),(Myj 51), the 40-oxyethylene stearate ester (Mydj 52) and mixturesthereof. Suitable bile salts include sodium cholate, sodium salts oflaurocholic, glycolic and desoxycholic acids and mixtures thereof.

Suitable terpenes include D-limonene, α-pinene, β-enrene, α-terpineol,terpinen-4-ol, carvol, carvone, pulegone, piperitone, menthone, menthol,geraniol, cyclohexene oxide, limonene oxide, α-pinene oxide,cyclopentene oxide, 1,8-cineole, ylang oil, anise oil, chenopodium oil,eucalyptus oil and mixtures thereof. Suitable alkanones includeN-heptane, N-octane, N-nonane, N-decane, N-undecane, N-dodecane,N-tridecane, N-tetradecane, N-hexadecane and mixtures thereof. Suitableorganic acids include citric acid, succinic acid, salicylic acid,salicylates (including the methyl, ethyl and propyl glycol derivatives),tartaric acid and mixtures thereof.

In a preferred embodiment, the penetration enhancer is analkyl-2-(N-substituted amino)-alkanoate, an (N-substitutedamino)-alkanol alkanoate, or a mixture of these. For convenientreference, alkyl-2-(N-substituted amino)-alkanoates and (N-substitutedamino)-alkanol alkanoates can be grouped together under the label alkyl(N-substituted amino) esters.

Alkyl-2-(N-substituted amino)-alkanoates suitable for the presentinvention can be represented as follows:

wherein n is an integer having a value in the range of about 4 to about18; R is a member of the group consisting of hydrogen, C₁ to C₇ alkyl,benzyl and phenyl; R₁ and R₂ are members of the group consisting ofhydrogen and C₁ to C₇ alkyl; and R₃ and R₄ are members of the groupconsisting of hydrogen, methyl and ethyl.

Preferred are alkyl (N,N-disubstituted amino)-alkanoates such as C₄ toC₁₈ alkyl (N,N-disubstituted amino)-acetates and C₄ to C₁₈ alkyl(N,N-disubstituted amino)-propionates and pharmaceutically acceptablesalts and derivatives thereof. Exemplary specificalkyl-2-(N,N-disubstituted amino)-alkanoates include dodecyl 2-(N,Ndimethylamino)-propionate (DDAIP);

and dodecyl 2-(N,N-dimethylamino)-acetate (DDAA);

Alkyl-2-(N-substituted amino)-alkanoates are known. For example, dodecyl2-(N,N-dimethylamino)-propionate (DDAIP) is available from Steroids,Ltd. (Chicago, Ill.). In addition, alkyl-2-(N,N-disubstitutedamino)-alkanoates can be synthesized from more readily availablecompounds as described in U.S. Pat. No. 4,980,378 to Wong et al., whichis incorporated herein by reference to the extent that it is notinconsistent. As described therein, alkyl-2-(N,N-disubstitutedamino)-alkanoates are readily prepared via a two-step synthesis. In thefirst step, long chain alkyl chloroacetates are prepared by reaction ofthe corresponding long chain alkanols with chloromethyl chloroformate orthe like in the presence of an appropriate base such as triethylamine,typically in a suitable solvent such as chloroform. The reaction can bedepicted as follows:

wherein R, R₃, R₄ and n are defined as above. The reaction temperaturemay be selected from about 10 degrees Celsius to about 200 degreesCelsius or reflux, with room temperature being preferred. The use of asolvent is optional. If a solvent is used, a wide variety of organicsolvents may be selected. Choice of a base is likewise not critical.Preferred bases include tertiary amines such as triethylamine, pyridineand the like. Reaction time generally extends from about one hour tothree days.

In the second step, the long chain alkyl chloroacetate is condensed withan appropriate amine according to the scheme:

wherein n, R, R₁, R₂, R₃ and R₄ are defined as before. Excess aminereactant is typically used as the base and the reaction is convenientlyconducted in a suitable solvent such as ether. This second step ispreferably run at room temperature, although temperature may vary.Reaction time usually varies from about one hour to several days.Conventional purification techniques can be applied to ready theresulting ester for use in a pharmaceutical compound.

Suitable (N-substituted amino)-alkanol alkanoates can be represented bythe formula:

wherein n is an integer having a value in the range of about 5 to about18; y is an integer having a value in the range of 0 to about 5; and R₁,R₂, R₃, R₄, R₅, R₆, and R₇ are members of the group consisting ofhydrogen, C₁ to C₈ alkyl, and C₁ to C₈ aryl; and R₈ is a member of thegroup consisting of hydrogen, hydroxyl, C₁ to C₈ alkyl, and C₁ to C₈aryl. The preparation of suitable (N-substituted amino)-alkanolalkanoates and their advantages over previously known penetrationenhancers are disclosed in published international patent application WO95/09590.

Preferred are (N-substituted amino)-alkanol alkanoates such as C₅ to C₁₈carboxylic acid esters and pharmaceutically acceptable salts thereof.Exemplary specific (N,N-disubstituted amino)-alkanol alkanoates include

1-(N,N-dimethylamino)-2-propanol dodecanoate (DAIPD);

1-(N,N-dimethylamino)-2-propanol myristate (DAIPM);

1-(N,N-dimethylamino)-2-propanol oleate (DAIPO);

The (N,N-disubstituted amino)-alkanol alkanoates are readily prepared byreacting the corresponding aminoalkinol with lauroyl chloride in thepresence of triethylamine. A solvent such as chloroform is optional butpreferred. For example, 1-(N,N-dimethylamino)-2-propanol can be reactedwith lauroyl chloride in chloroform and in the presence of triethylamineto form 1-(N,N-dimethyl-amino)-2-propanol dodecanoate (DAIPD). Among thesuitable penetration enhancers for the present invention DDAIP isgenerally preferred.

The penetration enhancer is present in an amount sufficient to enhancethe penetration of the prostaglandin E₁. The specific amount variesnecessarily according to the desired release rate and the specific formof prostaglandin E₁ used. Generally, this amount ranges from about 0.5percent to about 10 percent, based on the total weight of thecomposition. In one embodiment, where the vasoactive prostaglandin isprostaglandin E₁, the penetration enhancer is DDAIP in the amount ofabout 0.01 to about 5 weight percent of the composition.

Additionally, other known transdermal penetration enhancers can also beadded, if desired. Illustrative are dimethyl sulfoxide (DMSO), dimethylacetamide (DMA), 2-pyrrolidone, N,N-diethyl-m-toluamide (DEET),1-dodecylazacycloheptane-2-one (Azone™, a registered trademark of NelsonResearch), N,N-dimethylformamide, N-methyl-2-pyrrolidone, calciumthioglycolate, oxazolidinone, dioxolane derivatives, laurocapramderivatives, and macrocyclic enhancers such as macrocyclic ketones.

Natural and modified polysaccharide gums are also an importantingredient of the composition. Suitable representative gums are those inthe natural and modified galactomannan gum category. A galactomannan gumis a carbohydrate polymer containing D-galactose and D-mannose units, orother derivatives of such a polymer. There is a relatively large numberof galactomannans, which vary in composition depending on their origin.The galactomannan gum is characterized by a linear structure ofβ-D-mannopyranosyl units linked (1→4). Single membered α-D-manopyranosylunits, linked (1→6) with the main chain, are present as side branches.Galactomannan gums include guar gum, which is the pulverized endospermof the seed of either of two leguminous plants (Cyamposis tetragonalobusand psoraloids) and locust bean gum, which is found in the endosperm ofthe seeds of the carobtree (ceratonia siliqua). Suitable modifiedpolysaccharide gums include ethers of natural or substitutedpolysaccharide gums, such as carboxymethyl ethers, ethylene glycolethers and propylene glycol ethers. An exemplary substitutedpolysaccharide gum is methylcellulose.

Other suitable representative gums include agar gum, carrageenan gum,ghatti gum, karaya gum, rhamsan gum and xanthan gum. The composition ofthe present invention may contain a mixture of various gums, or mixtureof gums and acidic polymers.

Gums, and galactomannan gums in particular, are well-known materials.See for instance, Industrial Gums: Polysaccharides & Their Derivatives,Whistler R. L. and BeMiller J. N. (eds.), 3rd Ed. Academic Press (1992)and Davidson R. L., Handbook of Water-Soluble Gums & Resins,McGraw-Hill, Inc., N.Y. (1980). Most gums are commercially available invarious forms, commonly a powder, and ready for use in foods and topicalcompositions. For example, locust bean gum in powdered form is availablefrom Tic Gums Inc. (Belcam, Md.).

When present, the polysaccharide gums are present in the range fromabout 0.1 percent to about 5 percent, based on the total weight of thecomposition, with the preferred range being from 0.5 percent to 3percent. In one preferred embodiment, 2.5 percent by weight of apolysaccharide gum is present. Illustrative compositions are given inthe examples, below.

An optional alternative to the polysaccharide gum is a polyacrylic acidpolymer. A common variety of polyacrylic acid polymer is knowngenerically as “carbomer.” Carbomer is polyacrylic acid polymers lightlycross-linked with polyalkenyl polyether. It is commercially availablefrom the B. F. Goodrich Company (Akron, Ohio) under the designation“CARBOPOL™.” A particularly preferred variety of carbomer is thatdesignated as “CARBOPOL 940.”

Other polyacrylic acid polymers suitable for use are those commerciallyavailable under the designations “Pemulen™” (B. F. Goodrich Company) and“POLYCARBOPHIL™” (A. H. Robbins, Richmond, Va.). The Pemulen™ polymersare copolymers of C₁₀ to C₃₀ alkyl acrylates and one or more monomers ofacrylic acid, methacrylic acid or one of their simple esters crosslinkedwith an allyl ether of sucrose or an allyl ether of pentaerythritol. ThePOLYCARBOPHIL™ enhancer is a polyacrylic acid cross-linked with divinylglycol.

Where polyacrylic acid polymers are present, they represent about 0.5percent to about 5 percent of the composition, based on its totalweight.

Semi-solid compositions and penetration enhancers suitable for thepractice of the present invention are described in detail in U.S. Pat.Nos. 6,046,244, 6,118,020 and 6,323,241, the teachings of which areincorporated herein by reference.

The semi-solid composition has a suitably chosen viscosity such that thecomposition is naturally retained at the site of administration. Thesemi-solid composition can exhibit Newtonian or non-Newtonianrheological characteristics. In some preferred embodiments, thesemi-solid composition of the present invention exhibits non-Newtonianrheological characteristics, i.e. in which the apparent viscosity isdependent on the shear rate applied to the composition. Preferably thecomposition has “shear-thinning” rheological properties. As used herein,“shear-thinning” refers to a reduction in apparent viscosity (the ratioof shear stress to the shear rate) with increasing shear rate, whetherthe reduction in apparent viscosity is time independent (pseudoplastic),time dependent (thixotropic) or associated with a yield stress, definedas a stress that must be exceeded before flow starts, (Bingham plasticsand generalized Bingham plastics). See, generally, Harris, J., &Wilkinson, W. L., “Non-Newtonian Fluid,” pp. 856-858 in Parker, S. P.,ed., McGraw-Hill Encyclopedia of Physics, Second Edition, McGraw-Hill,New York, 1993. A suitable viscosity range of the composition is fromabout 5,000 centipoise (cps) to about 20,000 cps, preferably from about7,000 cps to about 13,000 cps.

Another important component is a lipophilic component. As used herein“lipophilic component” refers to an agent that is both lipophilic andhydrophilic. One of ordinary skill in the pharmaceutical arts willunderstand that the lipophilic nature, or “lipophilicity” of a givencompound is routinely quantified for comparison to other compounds byusing the partition coefficient. The partition coefficient is defined bythe International Union of Pure and Applied Chemistry (IUPAC) as theratio of the distribution of a substance between two phases when theheterogeneous system (of two phases) is in equilibrium; the ratio ofconcentrations (or, strictly speaking, activities) of the same molecularspecies in the two phases is constant at constant temperature.

The C₁ to C₈ aliphatic alcohols, the C₂ to C₃₀ aliphatic esters, andtheir mixtures can serve as lipophilic component. Illustrative suitablealcohols are ethanol, n-propanol and isopropanol, while suitable estersare ethyl acetate, butyl acetate, ethyl laurate, methyl propionate,isopropyl myristate and isopropyl palmitate. As used herein, the term“aliphatic alcohol” includes polyols such as glycerol, propylene glycoland polyethylene glycols. In one embodiment, a mixture of alcohol andester is preferred, and in particular, a mixture of ethanol and ethyllaurate is preferred. In another embodiment, about 0.1 to about 10percent by weight isopropyl myristate, preferably about 3 percent byweight isopropyl myristate is substituted for ethyl laurate. In someembodiments, the lipophilic component includes at least one liquidpolyol. In preferred embodiments, the liquid polyol is a polyethyleneglycol selected from the group consisting of polyethylene glycol 200,polyethylene glycol 400 and polyethylene glycol 600. When polyethyleneglycol is used, polyethylene glycol is present in the amount of about 1weight percent to about 25 weight percent, based on the total weight ofthe composition. A preferred polyethylene glycol is polyethylene glycol400 (PEG 400). When present, polyethylene glycol 400 is about 1 weightpercent to about 25 weight percent, preferably about 3 weight percent toabout 20 weight percent, based on the total weight of the composition.

In one embodiment, the C₂ to C₃₀ aliphatic esters, and their mixturescomprising the lipophilic component include CB to C₃₀ aliphatic estersof glycerol selected from the group consisting of monoglycerides,diglycerides, triglycerides, and mixtures thereof. Suitable aliphaticesters include glyceryl esters of saturated fatty acids, unsaturatedfatty acids and mixtures thereof. Suitable saturated fatty acids includecaproic acid, caprylic acid, capric acid, lauric acid, myristic acid,palmitic acid, stearic acid, arachidic acid, behenic acid and lignocericacid. In a preferred embodiment, about 0.1 to about 5 percent,preferably about 1 weight percent lauric acid is present. Suitableunsaturated fatty acids include oleic acid, linoleic acid and linolenicacid. Suitable glyceryl esters include glyceryl monooleate, triolein,trimyristin and tristearin, perferably trimyristin.

The concentration of lipophilic component required necessarily variesaccording to other factors such as the desired semi-solid consistencyand the desired skin penetration promoting effects. Suitably theconcentration of lipophilic component is in the range of 0.5 percent to40 percent by weight based on the total weight of the composition. Thepreferred topical composition contains lipophilic component in the rangeof 7 percent to 40 percent by weight based on the total weight of thecomposition.

Where a mixture of aliphatic alcohol and aliphatic ester are employed,the suitable amount of alcohol is in the range of 0.5 percent to 10percent. In one preferred embodiment, the amount of alcohol is in therange of 5 percent to 15 percent, while that of aliphatic ester is inthe range from 2 percent to 15 percent (again based on the total weightof the composition). In another preferred embodiment, the amount ofalcohol is in the range of 0.5 percent to 10 percent, while that ofaliphatic ester is in the range from 0 percent to 10 percent (againbased on the total weight of the composition).

The concentration of lipophilic component required necessarily variesaccording to other factors such as the desired semi-solid consistencyand the desired skin penetration promoting effects. The preferredtopical composition contains lipophilic component in the range of 7percent to 40 percent by weight based on the total weight of thecomposition. Where a lipophilic component that is a mixture of aliphaticalcohol and aliphatic ester is used, the preferred amount of alcohol isin the range of 5 percent to 15 percent, while that of aliphatic esteris in the range from 2 percent to 15 percent (again based on the totalweight of the composition).

An optional, but preferred, component is an emulsifier. Although not acritical factor, a suitable emulsifier generally will exhibit ahydrophilic-lipophilic balance number greater than 10. Sucrose esters,and specifically sucrose stearate, can serve as emulsifiers for thecomposition. Sucrose stearate is a well-known emulsifier available fromvarious commercial sources. When an emulsifier is used, sucrose stearatepresent up to about 2 percent, based on the total weight of thecomposition, is preferred. The preferred amount of sucrose stearateemulsifier can also be expressed as a weight ratio of emulsifier topolysaccharide gum. A ratio of 1 to 6 emulsifier to gum is preferred,and a ratio of 1 to 4 is most preferred to generate the desiredsemi-solid consistency and separation resistance.

Other emulsifiers are also suitable including polyoxyethylene sorbitanesters, long chain alcohols, preferably cetostearyl alcohol, and fattyacid glycerides. Suitable polyoxyethylene sorbitan esters include themonolaurate (Tween 20, Span 20) the monopalmitate (Tween 40), themonostearate (Tween 60), and the monooleate (Tween 80) and mixturesthereof. Preferred fatty acid glycerides include glyceryl monooleate,triolein, trimyristin and tristearin.

The composition includes an acid buffer system. Acid buffer systemsserve to maintain or buffer the pH of compositions within a desiredrange. The term “buffer system” or “buffer” as used herein has referenceto a solute agent or agents which, when in a water solution, stabilizesuch solution against a major change in pH (or hydrogen ionconcentration or activity) when acids or bases are added thereto. Soluteagent or agents which are thus responsible for a resistance to change inpH from a starting buffered pH value in the range indicated above arewell known. While there are countless suitable buffers, potassiumphosphate monohydrate has proven effective for compositions of thepresent invention.

The final pH value of the pharmaceutical composition may vary within thephysiologically compatible range. Necessarily, the final pH value is notirritating to human skin. Without violating this constraint, the pH maybe selected to improve prostaglandin E₁ stability and to adjustconsistency when required. In one embodiment, the preferred pH value isabout 3 to about 7.4, more preferably about 3.0 to about 6.5, mostpreferably from about 3.5 to about 6.0.

The remaining component of the composition is water, which isnecessarily purified. The composition contains water in the range ofabout 50 to about 90 percent, based on the total weight of thecomposition. The specific amount of water present is not critical,however, being adjustable to obtain the desired consistency and/orconcentration of the other components.

Prostaglandin E₁ stabilizers, coloring agents, Theological agents, andpreservatives can be added to the extent that they do not overly limitprostaglandin E₁ skin penetration or prevent the desired semi-solidconsistency.

Contemplated dosage forms of the semi-solid pharmaceutical compositionare creams, gels, ointments, colloidal suspensions and the like, alsoincluding but not limited to compositions suitable for use withtransdermal patches and like devices.

The ingredients listed above may be combined in any order and mannerthat produces a stable composition comprising a prostaglandin E₁ evenlydispersed throughout a semi-solid formulation. One available approach topreparing such compositions involves evenly dispersing thepolysaccharide gum (or polyacrylic acid polymer) in a premixedwater/buffer solution and then thoroughly homogenizing (i.e. mixing) theresulting mixture, which can be labeled “Part A.” When present, theemulsifier is added to the water/buffer solution before dispersing thepolysaccharide gum. Any suitable method of adjusting the pH value ofPart A to the desired level may be used, for example, by addingconcentrated phosphoric acid or sodium hydroxide.

Separately, the prostaglandin E₁ is dissolved with agitation in thelipophilic component, which itself may be a mixture of alcohols, esters,or alcohol with ester. Next, the penetration enhancer is added.Alternatively, when the lipophilic component includes both an alcoholand an ester, the prostaglandin E₁ can be dissolved in the alcoholbefore adding the penetration enhancer followed by the ester. In eithercase, the resulting mixture can be labeled “Part B.” The final stepinvolves slow addition (e.g. dropwise) of Part B into Part A underconstant mixing.

The resulting topical composition, when compared to exhibits theadvantageous properties described above, including improvedprostaglandin E₁ permeation and bioavailability without drugoverloading, reduced skin damage and related inflammation, and increasedflexibility in design of dosage forms. These compositions can be usedfor prolonged treatment of peripheral vascular disease, male impotencyand other disorders treated by prostaglandin E₁, while avoiding the lowbioavailability and rapid chemical decomposition associated with otherdelivery methods. Application of prostaglandin E₁ in a topicalcomposition to the skin of a subject allows a predetermined amount ofprostaglandin E₁ to be administered continuously to the subject andavoids undesirable effects present with a single or multipleadministrations of larger dosages by injection. By maintaining asustained dosage rate, the prostaglandin E₁ level in the subject'starget tissue can be better maintained within the optimal therapeuticrange.

In one embodiment, a composition comprises about 0.01 percent to about 5percent modified polysaccharide gum; about 0.001 percent to about 1percent of a prostaglandin selected from the group consisting of PGE₁,pharmaceutically acceptable salts thereof, lower alkyl esters thereofand mixtures thereof; about 0.5 percent to about 10 percent DDAIP orsalts thereof; about 0.5 percent to about 10 percent of a lower alcoholselected from the group consisting of ethanol, propanol, isopropanol andmixtures thereof; about 0.5 percent to about 10 percent on anesterselected from the group consisting of ethyl laurate, isopropylmyristate, isopropyl laurate and mixtures thereof; based on the weightof the composition, and an acid buffer. Preferably the composition alsocomprises up to about 2 percent sucrose stearate.

Optionally the composition also comprises up to about 5 percentemulsifier. Preferably, the composition also comprises up to about 2percent emulsifier. Suitable emulsifiers include polysorbates such asTweens, glyceryl monooleate, triolein, trimyristin and tristearin. Apreferred emulsifier is trimyristin.

The practice of the present invention is demonstrated in the followingexamples. These examples are meant to illustrate the invention ratherthan to limit its scope. Variations in the treating compositions whichdo not adversely affect the effectiveness of prostaglandin E₁ will beevident to one skilled in the art, and are within the scope of thisinvention. For example, additional ingredients such as coloring agents,anti-microbial preservatives, emulsifiers, perfumes, prostaglandin E₁stabilizers, and the like may be included in the compositions as long asthe resulting composition retains desirable properties, as describedabove. When present, preservatives are usually added in amounts of about0.05 to about 0.30%. Suitable preservatives include methylparabens(methyl PABA), propylparabens (propyl PABA) and butylhydroxy toluene(BHT). Suitable perfumes and fragrances are known in the art; a suitablefragrance is up to about 5 percent myrtenol, preferably about 2 percentmyrtenol, based on the total weight of the composition. The compositionsof the present invention can also include a small amount, about 0.01 toabout 4% by weight, of a topical anesthetic, if desired. Typical topicalanesthetics include lidocaine, dyclonine, dibucaine, pharmaceuticallyacceptable salts and mixtures thereof. In one preferred embodiment, thetopical anesthetic is about 0.5 percent dyclonine, based on the weightof the composition.

The pharmaceutical preparation is preferably in unit dosage form. Insuch form the preparation is subdivided into unit doses containingappropriate quantities of the active component. The unit dosage form isa packaged preparation, where the package containing the discretequantities of the pharmaceutical preparation is, e.g. a rigid plasticdispenser or flexible packet.

Another aspect of the invention is an article of manufacture thatcomprises a composition for treating erectile dysfunction as describedabove in a suitable container, preferably in a container such as thedispenser disclosed in U.S. Pat. No. 6,224,573, in combination withlabeling instructions. Alternatively, the container can be a tube with asuitable orifice size, such as an extended tip tube, pouch, packet, orsqueeze bottle and made of any suitable material, for example rigidplastic or flexible plastic.

The labeling instructions can come in the form of a pamphlet, a labelapplied to or associated with the packaging of the article ofmanufacture.

Unless otherwise indicated, each composition is prepared byconventionally admixing the respective indicated components together.

EXAMPLE 1 Exemplary Compositions

Exemplary Composition A was prepared as follows. Part A was formed bydissolving 0.4 parts prostaglandin E₁ (Alprostadil USP) in 5 parts ethylalcohol. Next, 5 parts dodecyl 2-(N,N-dimethylamino)-propionate weremixed into the alcohol-prostaglandin E₁ solution, followed by 5 partsethyl laurate.

Part B was prepared starting from a pH 5.5 water/buffer solution. Thewater/buffer solution was prepared by adding sufficient potassiumphosphate monohydride to purified water to create a 0.1 M solution. ThepH of the water/buffer solution was adjusted to 5.5 with a strong basesolution (1 N sodium hydroxide) and a strong acid (1 N phosphoric acid).The buffer solution represented about 80 parts of the total composition.All parts specified herein are parts by weight.

To the buffer solution was added 0.5 parts ethyl laurate. Next, thelocust bean gum (in powder form) was dispersed in the buffer solutionand homogenized using a homogenizer. Table 1, below, contains a list ofingredients.

The resulting composition was a spreadable, semi-solid suitable forapplication to the skin without the need for supporting devices such aspatches and adhesive strips. The composition was both homogenous inappearance and resistant to separation. TABLE 1 Topical Prostaglandin E₁Compositions Ingredient (wt %) A B C D E F G H I prehydrated locust beangum 3 3 3 3 3 3 3 — — prehydrated modified guar gum — — — — — — — 3 —Xanthan gum — — — — — — — — 2 water/buffer (pH 5.5) 81 81 81 81 81 81 8181 82.7 sucrose stearate 0.5 0.5 0.5 0.5 0.5 0.5 0.5 — — prostaglandinE₁ 0.1 0.2 0.3 0.4 0.4 0.5 0.4 0.3 0.4 DDAIP 5 5 5 5 5 5 5 2.5 1.8ethanol 5 5 5 5 5 5 10 5 5 ethyl laurate 5 5 5 5 5 5 — 3 — Isopropylmyristate — — — — — — — — 3 triethanolamine — — — — — — — — 0.5 lauricacid — — — — — — — — 1

Additional exemplary compositions B-I are prepared in the same mannerusing

the components listed in Table 1. As noted above, in other embodiments,such as Composition H, the composition may include a modifiedpolysaccharide gum, suitably a modified galactomannan gum, such as aguar gum. Alternatively, a polyacrylic acid polymer may be used insteadof the polysaccharide gum.

EXAMPLE 2 Pharmacodynamic Study of a Topical PGE₁ Composition as anAntagonist for Vasospasm

The spasmolysis (reversal of vasospasm) and vasodilation effects of atopical PGE, composition (Composition H of Example 1 modified asappropriate to contain the indicated amount of PGE₁) on vasospasminduced by adrenalin hydrochloride were studied in vivo by monitoringvascular diameter changes in rabbit ears. TABLE 2 Drugs Used Drug NameSize Function Batch No. Supplier Sumianxin 1.5 ml/Ampule General20020425 Veterinary Research Institute Anesthesia of ChangchunAgricultural-Pastoral University Adrenaline HCl 1 mg/1 ml Vasospasm20010625 Tianjing People's Induction Pharmaceuticals Blank Sterile 0.0%PGE₁ Blank 020401 NexMed Cream Control Pharmaceuticals PGE₁ Sterile 0.4%PGE₁ Positive 020401 (Zhongshan), Ltd. Cream w/o penetration Controlenhancers 0.1% PGE₁ Test 020401 0.2% PGE₁ Composition 020401 0.4% PGE₁020401 0.8% PGE₁ 020401Note:Positive control was 0.4% PGE₁ sterile cream without DDAIP penetrationenhancer; all other PGE₁ cream preparations contained 2.5 wt% DDAIPpenetration enhancer. Sumianxin is a mixture of baodingning (5% dimethylaniline thiazole hydrochloride with 10% EDTA) and haloperidol.

New Zealand Rabbits, weight 2-3 kg, no gender preference, used in thestudy were provided by the Breed Branch of Beijing Yuancheng MiaomuCompany, Ltd., license No. SCK2002-004. General anesthesia was inducedby intramuscular injection of SUMLANXIN (0.3 ml/kg). A total of 60rabbits were randomly assigned into 6 groups with 10 rabbits per group.Testing was preformed at a constant room temperature of 20 degreesCelsius. Blood vessels were imaged and recorded using a Sony DSC-S75Digital Camera. Vessel diameters were measured using Adobe Photoshop 6.0Software.

After shaving and preparation of the rabbit ears, 0.05 ml of adrenalinehydrochloride (1 mg/ml) was injected into the tissue surrounding thecentral artery 1 cm above the base of the ear. The vasospasm wastypically observed about five minutes after the adrenalin injection. Asingle administration of 80 mg topical composition with various PGE,concentrations was applied onto the skin area, 0.5-2 cm above the earbase, 10 minutes after the appearance of the typical vasospasm in thecentral ear artery. Administration of PGE, at a concentration of 0.1,0.2, 0.4 and 0.8 weight percent provided respective doses of 80, 160,320 and 640 micrograms (μg) of PGE₁. Digital photographs were taken ofthe normal condition of the blood vessels after anesthesia, at 10minutes after vasospasm was induced, and at 10, 15, 30, 60, 90 and 120minutes after the administration of the various PGE, topicalcompositions.

The digital images were uploaded into a computer and analyzed usingAdobe Photoshop 6.0 software. The diameter of the central artery at apoint 1.5 cm above the base of the ear was measured with an accuracy of0.1 mm. The data are reported in Table 3, below, as meandiameter±standard deviation (SD); t-test was used for statisticalanalysis. TABLE 3 Vessel Diameter Before And After Administration ofCream Positive Blank Group 80 μg 160 μg 320 μg 640 μg Control Control N10 10 10 10 10 10 Normal 2.9 ± 0.13 2.5 ± 0.13 2.7 ± 0.12 2.8 ± 0.15 2.8± 0.17 2.8 ± 0.20 Condition after Anesthesia 10 minutes after 0.7 ± 0.140.5 ± 0.12 0.6 ± 0.11 0.4 ± 0.08 0.4 ± 0.12 0.6 ± 0.12 Vasospasm 10minutes after 1.1 ± 0.18 1.6 ± 0.12 2.5 ± 0.16 2.6 ± 0.09 1.4 ± 0.13 1.2± 0.16 Application 15 minutes after 2.0 ± 0.16 2.3 ± 0.15 2.8 ± 0.14 2.8± 0.16 1.4 ± 0.18 1.4 ± 0.15 Application 30 minutes after 2.1 ± 0.14 2.5± 0.16 2.8 ± 0.17 2.8 ± 0.13 1.4 ± 0.16 1.4 ± 0.22 Application 60minutes after 1.1 ± 0.18 2.1 ± 0.18 3.2 ± 0.18 3.2 ± 0.12 1.4 ± 0.16 1.5± 0.17 Application 90 minutes after 1.4 ± 0.16 2.1 ± 0.16 2.8 ± 0.19 3.2± 0.13 1.4 ± 0.14 1.5 ± 0.16 Application 120 minutes 1.7 ± 0.22 2.1 ±0.17 2.8 ± 0.20 2.8 ± 0.19 1.8 ± 0.24 2.0 ± 0.18 after Application

FIGS. 1A-1B shows images of the transilluminated shaved dorsal surfacesof the right (FIG. 1A) and left ears (FIG. 1B) of a rabbit. The twoarrows in each Fig. indicate the vasospasm that was observed 5 minutesafter injections of 2 ml of a 0.1% adrenaline solution into the tissuenext to the central arteries and veins near the base of both ears.

FIGS. 2A-2B show images of the transilluminated shaved dorsal surfacesof the right (FIG. 2A) and left ears (FIG. 2B) of the rabbit of FIG. 1about five minutes after topical application of 125 mg 0.4% topical PGE,composition onto the skin next to the central artery and vein near thebottom of the right ear (FIG. 2A). At 15 minutes post application, allblood vessels on the right ear were dilated, including the site of thevasospasm (between the two arrows. At 35 minutes after the application,all blood vessels were dilated normally and showed good circulation. Incomparison, the blood vessels of the left ear that was treated with theblank control remained in vasospasm (arrows, FIG. 2B).

The averaged data are reported in Table 3, above, as meandiameter±standard deviation (SD), N=10, and shown graphically in FIG. 3.FIG. 3 is a graphical representation of the averaged results of a studyof vasospasm in rabbit ears that is illustrated by FIG. 1 and FIG. 2. Asnoted above, a single administration of 80 mg topical composition withvarious PGE, concentrations was applied onto the skin area, 0.5-2 cmabove the ear base, 10 minutes after the typical time a vasospasmappeared in the central ear artery. Administration of the topicalcomposition comprising 0.1, 0.2, 0.4 or 0.8 weight percent PGE₁ providedrespective doses of 80 (filled circles), 160 (filled triangles), 320(“X”) and 640 (“*”) micrograms (μg) of PGE, as well as cream withoutPGE, (0 μg PGE₁, filled diamonds) and positive control (0.4% PGE,topical composition without penetration enhancer, filled circles).Digital photographs were taken of the normal condition of the bloodvessels after anesthesia, at 10 minutes after vasospasm was induced, andat 10, 15, 30, 60, 90 and 120 minutes after the administration of thevarious PGE, compositions. Data are presented as mean vesseldiameter±standard deviation. S* refers to the time of the vasospasm; A**refers to the time of the administration of topical composition. TABLE 4The Average Time (minutes) Required To Return To The Initial VesselDiameter. (N = 10 for each group) 320 μg without DDAIP (Positive 0 μgControl (Blank in This Control) Study) 80 μg 160 μg 320 μg 640 μg 120120 120 30 ± 16.37 15 ± 18.18 10 ± 11.11

The average time required to return to the initial vessel diameter isprovided in Table 4, above. The treatment with the blank controlcomposition (“0 μg PGE₁”), 0.4% PGE, topical composition without DDAIPpenetration enhancer and a topical composition comprising 80 μg PGE₁ didnot produce recovery of vessel diameter within the 120 minute durationof the test. Administration of topical compositions having higheramounts of PGE, produced recovery of vessel diameter and showed adose-dependent decrease in the time required for recovery. In thisstudy, there was a more than six-fold difference between compositionswith and without DDAIP at the 320 mg dose of PGE₁, a supra thresholdeffective dose. TABLE 5 The Duration (minutes) The Initial VesselDiameter Was Greater Than The Diameter Before Vasospasm. (N = 10 foreach group) 320 μg 0.4 wt % PGE₁ 0 μg without 0 wt % DDAIP PGE₁(Positive 80 μg 160 μg 320 μg 640 μg (Blank Control in 0.1 wt % 0.2 wt %0.4 wt % 0.8 wt % Control) This Study) PGE₁ PGE₁ PGE₁ PGE₁ 0 30 0 5 105120

The average time required to return to the initial vessel diameter isprovided in Table 5, above, showing additional vasodilation beyond thebaseline. The treatment with the blank control composition, 0.4% PGE,topical composition without DDAIP penetration enhancer and a topicalcomposition comprising 0.1 wt % PGE₁ did not produce any time within the120 minute duration of the test when the vessel diameter was greaterthan the pre-vasospasm value. Administration of topical compositionshaving higher amounts of PGE, resulted in dose-dependent dilation of thevessels. “Positive” indicates the result obtained with the compositionthat contained 320 μg (0.4 wt %) PGE₁ but lacked DDAIP. Note that inthis study there was more than a three-fold difference seen in theeffects of compositions with and without DDAIP with the same effectivedoses, 320 μm, of PGE₁.

At ten and fifteen minutes after administration of the drug: Compared toblank control group, the changes in vessel diameter produced by 80 μgPGE, cream and the positive control composition were not significant(P>0.05), but the changes in vessel diameter produced by the rest of theother PGE₁ compositions were significant at the P<0.01 level.Significant differences (P<0.01) were observed between all treatmentsexcept between 320 μg and 640 μg PGE, treatments (P>0.05).

At 30 minutes after administration of the drug: Compared to blankcontrol treatment, significant differences (P<0.01) in vascular diameterchanges were observed for treatment with each of the PGE, concentrationsexcept the positive control treatment (P>0.05). Among experimentaltreatments, significant differences (P<0.01) were observed between alltreatments except between 320 μg and 640 μg PGE₁ treatments (P>0.05).

At 60 minutes and at 90 minutes after administration of the drug:Compared to blank control treatment, significant differences (P<0.01) inthe vascular diameter changes were observed for treatment with each ofthe PGE, concentrations except the 80 μg treatment and the positivecontrol treatment (P>0.05). Among experimental treatments, significantdifferences (P<0.01) were observed between all treatments except between320 μg and 640 μg PGE, treatments (P>0.05).

At 120 minutes after administration of the drug: Compared to blankcontrol group, significant differences (P<0.01) of the vascular diameterchanges were observed for treatment with each of the PGE₁ concentrationsexcept the 80 μg, 160 μg PGE₁ and the positive control treatments(P>0.05). Among experimental groups, significant differences (P<0.01)were observed between all treatments except between 320 μg and 640 μgPGE₁ treatments (P>0.05).

The results showed that, compared to the blank control group,significant differences (P<0.01) were observed for 320 μg and 640 μgPGE, treatments at every time point, while no significant changes werefound between these latter two groups (P<0.05). While a dose-dependenteffect was observed in the range 0.2-0.8 weight percent PGE₁ for topicalcompositions having the DDAIP penetration enhancer, a topicalcomposition having 0.4 weight percent PGE, but lacking DDAIP had effectscomparable to those of the blank control that lacked PGE₁.

EXAMPLE 3 Laser Doppler Study of Vascular Perfusion Volume Charges inTreatment of Vasospasm Using a Topical PGE₁ Composition

The spasmolysis (reversal of vasospasm) and vasodilation effects of atopical PGE, composition (Composition H of Example 1 modified asappropriate to contain the indicated amount of PGE₁) on vasospasminduced by adrenalin hydrochloride were studied by monitoring vascularperfusion volume changes of central arteries of rabbit ears. Rabbitswere obtained and anesthetized and vasospasm induced as described inExample 2, above. A total of 60 rabbits were randomly assigned into 6groups with 10 rabbits per group.

Vascular perfusion volume and skin temperature were measured using thePeriFlux 5000 laser Doppler blood flowmetry system (Perimed AB,Stockholm, Sweden). As in Example 2, above, a single administration of80 mg topical composition with various PGE, concentrations was appliedonto the skin area, 0.5-2 cm above the ear base, 10 minutes after theappearance of the typical vasospasm in the central ear artery. The laserprobe was fixed at the area of central artery about 1.5 cm above the earbase. Measurements were made at time points of normal condition afteranesthesia, 10 minutes after vasospasm, 10 minutes, 15 minutes, 30minutes, 60 minutes, 90 minutes, and 120 minutes after administration ofthe drug. TABLE 6 The vascular perfusion volume changes before and afterthe drug administration (ml/min) Positive Blank Group 80 μg 160 μg 320μg 640 μg Control Control N 10 10 10 10 10 10 Normal 124 ± 4.90  128 ±4.45  127 ± 3.33 123 ± 3.06 127 ± 5.84  126 ± 4.69  Condition afterAnesthesia 10 minutes after 14 ± 1.49 17 ± 1.70  15 ± 1.94  13 ± 2.16 15± 3.16 12 ± 2.00 Vasospasm 10 minutes after 19 ± 1.16 40 ± 2.40 126 ±6.15  139 ± 10.84 25 ± 2.94 16 ± 2.06 Application 15 minutes after 20 ±1.94 90 ± 3.02 145 ± 6.70 170 ± 4.67 24 ± 1.70 20 ± 2.98 Application 30minutes after 97 ± 6.15 130 ± 5.94  152 ± 6.29 196 ± 5.87 25 ± 2.54 30 ±4.88 Application 60 minutes after 56 ± 7.69 85 ± 4.59 197 ± 3.97 205 ±2.79 29 ± 1.83 35 ± 5.03 Application 90 minutes after 63 ± 6.80 94 ±4.11 152 ± 4.88 196 ± 5.44 50 ± 6.93 48 ± 5.93 Application 120 minutes 95 ± 10.33 92 ± 3.68 146 ± 3.33 167 ± 7.10 62 ± 5.89 70 ± 7.33 afterApplication

The averaged data are reported in Table 6, above, as mean vascularperfusion volume±standard deviation (SD), N=10, and shown graphically inFIG. 4. FIG. 4 is a graphical representation of the averaged results ofa study of vascular perfusion volume in vasospasm in rabbit ears asmeasured by transcutaneous laser Doppler blood flowmetry. As notedabove, a single administration of 80 mg topical composition with variousPGE, concentrations was applied onto the skin area, 0.5-2 cm above theear base, 10 minutes after the typical time a vasospasm appeared in thecentral ear artery. Administration of the topical composition comprising0.1, 0.2, 0.4 or 0.8 weight percent PGE, provided respective doses of 80(filled circles), 160 (filled triangles), 320 (“X”) and 640 (“*”)micrograms (1 g) of PGE, as well as cream without PGE₁ (0 μg PGE₁,filled diamonds) and positive control (0.4% PGE, topical compositionwithout penetration enhancer, filled circles). Measurements were takenof the normal condition of the blood vessels after anesthesia, at 10minutes after vasospasm was induced, and at 10, 15, 30, 60, 90 and 120minutes after the administration of the various PGE, compositions. Dataare presented as mean±administration of topical composition. Positivecontrol, 0 μg and 80 μg groups did not achieve normal vascular perfusionby the study end point of 120 minutes after administration of the drug.TABLE 7 The Accumulated Change In Vascular Perfusion Volume Between 10Minutes After The Vasospasm To 120 Minutes After The Application Of theTopical Composition (ml/min, N = 10 for each group) 0 μg PGE₁ 80 μg 160μg 320 μg 640 μg 320 μg PGE₁ (Blank Control) PGE₁ PGE₁ PGE₁ PGE₁ withoutDDAIP 4595 ± 564 7590 ± 657 10960 ± 361 18550 ± 278 21753 ± 335 4356 ±213

The accumulated vascular perfusion volume that occurred between 10minutes after the vasospasm and 120 minutes after the application of thetopical composition is presented in Table 7, above. The treatment withthe blank control composition (“0 μg PGE₁”) and the positive control,0.4% PGE, topical composition without penetration enhancer producedsmall, comparable changes in vascular perfusion volume. Administrationof topical compositions having higher amounts of PGE, produced a greateraccumulated change in vascular perfusion volume and showed adose-dependent increase. TABLE 8 The Average Time Required To Return ToThe Initial Vascular Perfusion Volume (Minutes, N = 10 for each group) 0μg PGE₁ 20 μg PGE₁ 80 μg 160 μg 320 μg 640 μg (Blank Control) withoutDDAIP PGE₁ PGE₁ PGE₁ PGE₁ 120 120 120 30 10 7

The average time required after administration of the topicalcomposition to return to the initial vascular perfusion volume arepresented in Table 8, above. The treatment with the blank controlcomposition (“0 μg PGE₁”), 0.4% PGE, topical composition withoutpenetration enhancer and a topical composition comprising 80 μg PGE₁ didnot produce recovery of vascular perfusion volume within the 120 minuteduration of the test. Administration of topical compositions havinghigher amounts of PGE₁ produced recovery of vascular perfusion volumeand showed a dose-dependent decrease in the time required for recovery.

Ten to ninety minutes after administration of the drug: Compared toblank control group, no significant differences (P>0.05) of vascularperfusion changes of positive control group was noticed, whilesignificant differences (P<0.01) of vascular perfusion changes of otherPGE, concentration groups were observed.

One hundred and twenty minutes after administration of the drug:Compared to blank control group, significantly different (P<0.01)vascular perfusion changes were observed for all of the PGE₁concentration groups. Compared to 160 g PGE₁ group, significantlydifferent (P<0.01) vascular perfusion changes were observed for all ofthe PGE₁ concentration groups except positive control and 80 μg PGE₁concentration groups (P<0.01).

The experimental results indicated topical application of PGE₁ sterilecream is an effective antagonist for adrenaline-induced vasospasm andvascular perfusion changes. A dose-dependent relationship was observedfor PGE₁ in the concentration range of 80 μg to 640 μg.

EXAMPLE 4 Pharmacodynamic Study of a Study of a Topical PGE₁ Compositionas an Antagonist for Vasospasm During Surgical Operation in Rabbit

The spasmolysis (reversal of vasospasm) and vasodilation effects of atopical PGE₁ composition (Composition H of Example 1 modified asappropriate to contain the indicated amount of PGE₁) on vasospasminduced by adrenaline hydrochloride were studied by monitoring vasculardiameter changes in rabbit ears.

Rabbits were obtained and anesthetized as described in Example 2, above.A total of 70 rabbits were randomly assigned into 7 groups with 10rabbits per group.

Blood flow velocity and vascular cross section area were measured andanalyzed using a Toshiba Multifunction Ultrasonography 6000 system.

A portion of femoral artery about 2 cm long was exposed through a 3 cmincision. Four drops of adrenaline hydrochloride (1 mg/l ml) weredropped by a 1 ml syringe onto the surface of center of the exposedsegment of femoral artery to induce vasospasm. The entire test wasperformed under a constant room temperature of 20 degrees Celsius. Aboutten minutes after the application of adrenaline hydrochloride, theoperating field was irrigated with sterile saline topically and driedwith sterile pad. A single administration of 40 mg topical compositionwith various PGE₁ concentrations was applied onto the surface of the 2cm portion of the isolated femoral artery. A single administration offour drops of papaverine (30 mg/ml) from a 1 ml syringe onto this fieldwas used as a positive control.

The incision was closed after the application of the topicalcomposition. The ultrasonic probe was put at a fixed location 1 cm fromthe incision. The values of the blood flow velocity and vascular crosssections were recorded by the Toshiba Multifunction Ultrasonography attime points of normal condition after anesthesia, 5 minutes and 10minutes after vasospasm, 5 minutes, 10 minutes, 15 minutes, 30 minutes,60 minutes, 90 minutes, and 120 minutes after administration of thedrug. In general, blood flow volume=blood flow velocity×vascular crosssection

The data were expressed as average±SD; t-test was used for statisticalanalysis. The averaged data are reported in Table 9, below, asinstantaneous blood flow volume±standard deviation (SD), N=10, and showngraphically in FIG. 6. TABLE 9 The instantaneous blood flow volumechanges before and after the drug administration (mm³/s) 160 μg w/oBlank Group 40 μg 80 μg 160 μg 320 μg DDAIP Papaverine Control N 10 1010 10 10 10 10 Normal 326 ± 14.40 318 ± 14.92 327 ± 13.22 321 ± 12.75332 325 ± 9.80  330 ± 15.09 Condition 5 min after 104 ± 5.64  105 ±5.48  109 ± 4.74  107 ± 5.56  105 107 ± 4.11  108 ± 6.70  Vasospasm 10min after 87 ± 5.66 86 ± 5.10 82 ± 4.14 87 ± 4.32 84 86 ± 4.76 84 ± 5.94Vasospasm 5 min after 206 ± 10.54 230 ± 11.16 816 ± 23.12 364 ± 14.92142 319 ± 13.27 149 ± 8.68  Drug 10 min 251 ± 15.36 292 ± 13.14 769 ±24.97 254 ± 25.30 182 358 ± 13.95 132 ± 10.04 after Drug 15 min 289 ±18.55 292 ± 12.45 654 ± 22.50 582 ± 24.58 247 402 ± 18.44 146 ± 8.43 after Drug 30 min 183 ± 13.86 413 ± 14.28 490 ± 16.29 649 ± 25.97 290435 ± 17.76 197 ± 12.53 after Drug 60 min 214 ± 12.57 307 ± 12.06 462 ±17.68 809 ± 27.46 256 296 ± 12.58 210 ± 16.44 after Drug 90 min 262 ±13.56 290 ± 12.06 455 ± 12.61 562 ± 25.70 274 287 ± 11.96 254 ± 16.73after Drug 120 min 287 ± 14.16 271 ± 10.89 451 ± 11.42 541 ± 23.06 279274 ± 10.88 266 ± 18.29 after Drug

FIG. 6 is a graphical representation of the averaged results of vascularperfusion volume in rabbit femoral artery as measured byultrasonography. As noted above, a single administration of 40 mg oftopical composition with various PGE, concentrations was applied to thesurface of a surgically exposed portion of a femoral artery, 10 minutesafter the application of adrenaline hydrochloride. Administration of thetopical composition comprising 0.1, 0.2, 0.4 or 0.8 weight percent PGE,provided respective doses of 80 (filled circles), 80 (filled triangles),160 (“X”) and 320 (“*”) micrograms (μg) of PGE₁ as well as cream withoutPGE, (0 μg PGE₁, filled diamonds), (0.4% PGE₁ topical compositionwithout penetration enhancer, filled circles) and a positive control of4 drops of 30 mg/ml papaverine. Measurements were taken of the normalcondition of the blood vessels after anesthesia, at 5 and 10 minutesafter vasospasm was induced, and at 5, 10, 15, 30, 60, 90 and 120minutes after the administration of the various PGE, compositions. Dataare presented as mean±standard deviation. S* refers to the time of thevasospasm; A** refers to the time of the administration of topicalcomposition. The composition lacking the penetration enhancer DDAIPshowed significantly lesser effect than the composition having the samedose of PGE, with DDAIP. TABLE 10 The accumulated blood flow volume(cm³) from 10 minutes after vasospasm to 120 minutes after drugadministration (N = 10 for each group) 0 μg PGE₁ (Blank 40 μg 80 μg 160μg 320 μg Control) PGE₁ PGE₁ PGE₁ PGE₁ Papaverine 1525 ± 100.78 1686 ±95.85 2243 ± 85.46 3598 ± 106.98 4466 ± 175.71 2341 ± 94.87

The accumulated blood flow volume that occurred between 10 minutes afterthe vasospasm and 120 minutes after the application of the topicalcomposition is presented in Table 10, above. The treatment with theblank control composition (“0 μg PGE₁”) and a composition comprising 40μg PGE, produced small, comparable changes in vascular perfusion volume.Administration of papaverine produced a slightly greater effect that wascomparable to that produced by composition comprising 80 μg PGE₁.Administration of topical compositions having higher amounts of PGE,produced a greater accumulated change in blood flow volume and showed adose-dependent increase. TABLE 11 The Average Time Required To Return ToThe Initial Blood Flow Volume (Minutes, N = 10 for each group) 0 μg PGE₁80 μg 160 μg 320 μg (Blank Control) 40 μg PGE₁ PGE₁ PGE₁ PGE₁ Papaverine120 120 15 5 5 5

The average times required after administration of the topicalcomposition to return to the initial blood flow volume are presented inTable 11, above. The treatment with the blank control composition (“0 μgPGE₁”) and the 40 μg PGE, composition did not produce a recovery ofblood flow volume within the 120 minute duration of the test.Administration of topical compositions having higher amounts of PGE₁produced recovery of blood flow volume as did papaverine.

At 10 to 90 minutes after administration of the drug: Compared to blankcontrol group, significant differences (P<0.01) of instantaneous bloodflow volume (mm³/s) of all PGE₁ concentration groups were observed.

At 120 minutes after administration of the drug: Compared to blankcontrol group, significant differences (P<0.01) of instantaneous bloodflow volume (mm³/s) of all PGE, concentration groups were observedexcept 40 μg, 80 μg, and positive control groups (P>0.05).

The experimental results indicated application of PGE, sterile creamdirectly to the exposed surface of a blood vessel could effectivelycounteract the adrenaline induced instantaneous blood flow volumechanges and improve topical blood flow. The vascular dilation effect ofPGE₁ sterile cream appears to be better than papaverine. Adose-dependent relationship was observed for PGE, between theconcentration range of 80 μg to 320 μg.

EXAMPLE 5 Result of Pilot Studies on Topical Applications of A SpeciallyFormulated 0.4% PGE₁ Topical Composition

The objects of these pilot studies were designed to explore the efficacyof a specially formulated 0.4 wt % PGE₁ topical composition for treatingvasospasm and skin disorders that result from insufficient local bloodcirculation. Twenty four adult New Zealand rabbit, 3-4 kg, were dividedinto three groups: 12 rabbits were assigned into a Test Study Group; 6rabbits were assigned into a PGE₁ Control Group and 6 rabbits wereassigned into an Alcohol Control Group. One rabbit of each Group wasselected to enter the study at the same time for each of the first sixstudies.

The rabbit's right ear was selected to be the test application site,while its left ear was observed as a control. An adrenaline solution(0.2 ml of a 0.1% (1:1000) solution) was injected into the area adjacentto both the central artery and vein near the bottom of both ears.Classic vasospasm appeared five minutes later on both ears. One of threetest substances, 125 mg of a 0.4% PGE, topical composition containing1.8% DDAIP HCl was applied to a 2 cm×2 cm area of skin adjacent to thecentral artery and vein of the right ear.

Vasospasm was induced in the same way in both ears of the rabbits of thePGE₁ Control Group and the Alcohol Control Group. Similarly, 1 mg ofPGE₁ dissolved in 75% aqueous ethanol, or the 75% aqueous ethanolvehicle alone were applied to the right ears of the rabbits of the PGE,Control Group and the Alcohol Control Group respectively. The timecourse of changes in blood vessel diameter was observed.

In the Test Study Group, the vasospasm was alleviated five minutes afterthe 0.4 wt % PGE₁ topical composition was applied to the skin of theright ear. The vessels of the right ear were obviously dilated 15minutes later. The vascular bed of the right ear was also dilated andreaching a maximum at 30 minutes after application. The blood flow ofthe right ear increased obviously. The effect lasted two hours thendisappeared gradually. The vasospasm of the left ear alleviatedspontaneously two hours later.

In the PGE₁ Control Group, the vasospasm was alleviated slightly 20minutes after the application of PGE₁ onto the skin of the right ear.The vessels of the right ear were dilated 30 minutes later. The dilationeffect lasted 60 minutes then disappeared. No significant remainingchanges were observed of the vascular bed of the right ear. Thevasospasm of the left ear lasted two hours then disappearedspontaneously. In the Alcohol Control Group, the vasospasm wasalleviated slightly 10 minutes after the application of 75% Alcohol ontothe skin of the right ear. The vasospasm disappeared 90 minutes later.No significant remaining changes were observed of the vascular bed ofthe right ear. The vasospasm of the left ear lasted two hours thendisappeared automatically.

EXAMPLE 6 Topical Application to Improve and Prevent Local Vasospasmduring Surgery

The use of topical prostaglandin compositions during surgery for theprevention and treatment of local vasospasm was studied.

Approximately 125 mg of the topical prostaglandin composition H ofExample 2 containing 0.4% PGE, (dose 0.5 mg PGE₁) was applied to thevascular extima at the anastomotic site when local vasospasm appearedduring vascular anastomosis. The changes of local vascular and systemichemodynamics before and after vasospasm were observed and recorded.Eleven subjects were assigned to three groups.

Group 1 consisted of six subjects who needed arteriovenous fistularepair due to renal failure and for whom systemic application ofvasodilator was contraindicated due to several concomitant diseases.Approximately 125 mg of the topical prostaglandin composition wasapplied onto the vascular extima after shaping the arteriovenous fistuladuring arteriovenous anastomosis.

Group 2 contained two subjects who were emergency hand trauma patients,who had classic vasospasm right after the injury. Approximately 125 mgof the topical prostaglandin composition was applied onto the vascularextima at the anastomotic site after vascular anastomosis.

Group 3 consisted of three subjects who were vascular surgical patients.Vasospasm appeared in two subjects of Group 3 after vascular anastomosisperformed when removing a clot. Vasospasm appeared in the other Group 3subject after vascular anastomosis performed when removing vascularobliteration. Approximately 125 mg of the topical prostaglandincomposition was applied onto the vascular extima at the anastomotic siteafter vascular anastomosis.

No other vasodilators were given to the patients after the surgery.Changes of local vascular diameter were recorded by macroscopy using adigital camera. Laser Doppler flowmetry was also used to measure localhemodynamic changes.

The topical prostaglandin composition was applied after classicvasospasm appeared after vascular anastomosis and lasting for more than15 minutes without spontaneous alleviation. Typically, the vasospasm wasalleviated 2-5 minutes after the application of the topicalprostaglandin composition, and the blood vessel was obviously dilatedafter 10 minutes. The diameter of the blood vessel generally increasedto about twice that seen during the vasospasm; while the arterial pulseappeared to be reinforced as well. The dilation effect continued and wasalso observed at twenty minutes following application. Local blood flowas measured by laser Doppler blood flowmetry showed a five-fold increasein maximum local blood flow compared to prior to application of thetopical prostaglandin composition. No significant changes of bloodpressure and pulse were noted. No secondary vasospasm was noted in anypatient during the two-week observation period following surgery. Thewound healing progressed satisfactorily.

While the foregoing is intended to be illustrative of the presentinvention, the scope is defined by the appended claims. Numerousvariations and modifications may be effected without departing from thetrue spirit and scope of the invention.

1. A semi-solid composition comprising: a vasoactive prostaglandin; apenetration enhancer; a polymer thickener selected from the groupconsisting of a polysaccharide gum and a polyacrylic acid polymer; alipophilic component that is selected from the group consisting of analiphatic C₁ to C₈ alcohol, an aliphatic C₈ to C₃₀ ester, a liquidpolyol and a mixture thereof; water and a buffer system that provides abuffered pH value for said composition in the range of about 3 to about7.4. 2-21. (canceled) 22-28. (canceled)
 29. A method of improvingmicrocirculation in a replanted body part in a subject needing suchtreatment comprising the step of: applying to the vascular extima of theblood vessels an effective amount of a semi-solid composition comprisinga vasoactive prostaglandin; a penetration enhancer; a polymer thickenerselected from the group consisting of a polysaccharide gum and apolyacrylic acid polymer; a lipophilic component that is selected fromthe group consisting of an aliphatic C₁ to C₈ alcohol, an aliphatic C₈to C₃₀ ester, a liquid polyol and a mixture thereof; water and a buffersystem that provides a buffered pH value for said composition in therange of about 3 to about 7.4. 30-51. (canceled)
 52. A method ofimproving local microcirculation in a tissue comprising: applying to thesurface of the tissue an effective amount of a semi-solid composition,the composition comprising a vasoactive prostaglandin selected from thegroup consisting of prostaglandin E₁, prostaglandin E₂, apharmaceutically acceptable salt thereof, a lower alkyl ester thereofand a mixture thereof; a penetration enhancer selected from the groupconsisting of an alkyl-(N-substituted amino) ester elected from thegroup consisting of an alkyl-(N-substituted amino) alkanoate, analkyl-2-(N,N-disubstituted amino)alkanoate, an (N-substituted amino)alkanol alkanoate, an (N,N-disubstituted amino)alkanol alkanoate, apharmaceutically acceptable salt thereof and a mixture thereof; apolymer thickener selected from the group consisting of a polysaccharidegum and a polyacrylic acid polymer; a lipophilic component that isselected from the group consisting of an aliphatic C₁ to C₈ alcohol, analiphatic C₈ to C₃₀ ester, a liquid polyol and a mixture thereof; waterand a buffer system that provides a buffered pH value for saidcomposition in the range of about 3 to about 7.4.
 53. The method ofclaim 52 further comprising the step of applying the semi-solidcomposition to the vascular extima of the blood vessels supplying thetissue.
 54. The method of claim 52 wherein the surface to which thecomposition is applied is the surface of the skin.
 55. The method ofclaim 52 wherein the polysaccharide gum is a shear-thinningpolysaccharide gum.
 56. The method of claim 55 wherein theshear-thinning polysaccharide gum is a galactomannan gum.
 57. The methodof claim 55 wherein the shear-thinning polysaccharide gum is a modifiedgalactomannan gum.
 58. The method of claim 57 wherein the modifiedgalactomannan gum is a modified guar gum.
 59. The method of claim 52wherein the polymer thickener is a polyacrylic acid polymer.
 60. Themethod of claim 52 wherein the penetration enhancer is dodecyl2-(N,N-dimethylamino)-propionate or a pharmaceutically acceptable saltthereof.
 61. The method of claim 52 wherein the lipophilic componentcomprises at least one aliphatic C₈ to C₃₀ ester.
 62. A method ofpreventing reperfusion injury of an affected tissue comprising the stepsof: providing the composition of claim 1; and applying the compositionto the surface of the affected tissue.
 63. The method of claim 62further comprising the step of applying the composition to the vascularextima of blood vessels supplying the affected tissue.
 64. The method ofclaim 62 wherein the normal blood perfusion volume is restored in theaffected tissue in no more than ten minutes.